Treatment of Immune Disorders
Various methods have been described for the treatment of immune-related or immune mediated disorders or diseases, infectious diseases, metabolic disorders and different types of cancer in mammalian subjects. One of these methods involves the modulation of immune responses in a subject. This includes the down regulation of the immune response system using procedures or combinations of procedures for producing and applying a new and unexpected immune modulation termed selective immune down regulation (SIDR). Immunological modulation is an artificially induced variation in a subject's immune system in response to the introduction of reagents, procedures and processes. These procedures have been described in detail in U.S. patent application Ser. No. 08/808,629, filed on Feb. 28, 1997, U.S. patent application Ser. No. 10/377,628, filed on Mar. 4, 2003, U.S. application Ser. No. 10/377,603, filed on Mar. 4, 2003, U.S. patent application Ser. No. 09/447,704, filed on Feb. 28, 1997, U.S. application Ser. No. 10/385,440, filed on May 9, 2001, and U.S. application Ser. No. 09/356,294, filed on Jul. 16, 1999. Each if the foregoing patents are incorporated by reference in their entirety in the present application and may further be used in conjunction with the present invention.
NKT Cells
Natural killer T (NKT) lymphocytes are a subset of regulatory lymphocytes that co-express cell surface receptors characteristic of both T lymphocytes (e.g. CD3, α/β T cell receptor) and natural killer cells (e.g. NK1.1) (Godfrey et al. 2000, Immunol Today 2000; 21: 573). In mice, most NKT cells express the invariant Vα14Jα281 TCR chain, paired with a limited number of β chain types (Vβ8.2, Vβ7, and Vβ2) (Bendelac et al., 1997, Annu. Rev. Immunol. 15:535-56). In humans, distinct populations of NKT cells express the homologous invariant Vα24 paired with Vβ11 (Kim et al., 2002, Trends Immunol 23: 516-19). NKT lymphocytes are activated by interaction of their TCR with glycolipids presented by CD1d, a nonpolymorphic, MHC class I-like molecule expressed by antigen presenting cells. CD1d is also expressed by hepatocytes (Bleicher et al., 1990, Science 250: 679-82). While a natural CD1d-bound ligand capable of activating NKT cells has not been identified in mammals, α-galactosylceramide (α-GalCer, KRN-7000), a sponge-derived glycolipid, is a potent activator of both mouse and human NKT cells (Kawano et al., 1997, Science 278:1626). Administration of α-GalCer leads to rapid production of both IFNγ and IL-4 by NKT cells, with secondary activation of innate and adaptive immune responses (Chen et al., 1997, J Immunol 159: 2240 and Taniguchi et al., 2003, Nat Immunol. 4:1164-5). NKT cells also recognize glycosylphosphatidylinositol (GPI) anchors of Plasmodium, Trypanosoma and Leishmania, and phosphatidylinositol-mannosides derived from Mycobacterium tuberculosis (Godfrey et al., 2000, Immunol Today 21: 573).
Furthermore, NKT lymphocytes, have a role in various infectious, inflammatory, and neoplastic processes (Vincent et al., 2003, Nature Immunol 2003; 4: 517). These cells, which are abundant in the liver, are considered to be a link between innate and adaptive immune responses (Bendelac et al., 1997, Curr Opin Immunol 9:1-3), and were shown to have a role in a number of immune-mediated disorders. In NOD mice, reduced numbers of NKT cells are associated with increased susceptibility to diabetes (Baxter et al., 1997, Diabetes 46:572-82); in experimental allergic encephalomyelitis, activation of NKT attenuates the disease (Miyamoto et al., 2001, Nature 2001:413:531-4); in an animal model of systemic lupus erythematosus, a selective reduction in NKT cells precedes the development of autoimmune phenomena (Takeda et al., 1993, J Exp Med 177:155-64). NKT cells are known to induce hepatic injury in several models, including concanavalin A (Takeda et al., 2000, Proc. Natl. Acad. Sci. USA 97: 5498-5503 and Eberl et al., 1998, Immunity 9:345-353) and salmonella infection-induced liver damage.
Leptin-deficient ob/ob mice feature a dysfunctional immune response, manifested by depletion of hepatic NKT lymphocytes and impaired function of hepatic Kupffer cells (Lee et al., 1999, Am J Physiol 276:c386-c394; Loffreda et al., 1998, FASEB J 1998; 12:57-65 and Li et al., 2002, Gastroenterology 2002, 123:1304-1310). These alterations may explain the relatively increased sensitivity to LPS-induced hepatotoxicity and resistance to concanavalin A-induced hepatitis and experimental allergic encephalomyelitis observed in these animals (Matarese et al., 2001, J Immunol 166:5909-16).
Activation of NKT lymphocytes can lead to significant liver damage (Ogasawara et al., 1998; 160, 3522-27 and Osman et al., 2000, Eur J Immunol 30: 191). Concanavalin A, a plant lectin and T cell mitogen, rapidly induces severe immune-mediated hepatitis in mice, that is associated with increased TNFα, IFNγ, IL-12, IL-18, and IL-4 expression (Siebler et al., 2003, Hepatology 38:1573-80) and in which NKT lymphocytes, CD4+ T cells and Kupffer cells have a contributory role (Schumann et al., 2000, Am J Pathol 157: 1671-83). Vα14 NKT cells were shown to be required and sufficient for induction of this type of liver injury (Kaneko et al., 2000, J Exp Med 191:105-14). The cytotoxic activity of NKT lymphocytes is augmented by autocrine secretion of IL-4, leading to increased expression of granzyme B and Fas ligand by NKT lymphocytes; Vα14 NKT cells from perforin knockout or FasL-mutant gld/gld mice fail to induce hepatitis. In another study, adoptive transfer of NKT cells from wild-type, but not from FasL-deficient gld mice, sensitized CD1-deficient mice, which lack NKT cells, to Con A-induced hepatitis (Takeda et al., 2000, Proc Natl Acad Sci USA 97:5498-503). NKT cells also have a central role in lipopolisaccharide (LPS), α-GalCer, and salmonella infection-induced liver injury (Takahashi et al., 1996, J Immunol 156: 2436-42; Nakagawa et al., 2001, J Immunol 166: 6578-84 and Ishigami et al, 1999, Hepatology 29:1799-808), in hepatic injury secondary to deletion of suppressor of cytokine signaling-1 (SOCS-1) (Naka et al., 2001 Immunity 14: 535-45), and in hepatic damage in the setting of chronic hepatitis C infection and primary biliary cirrhosis (Yonekura et al., 2000, Liver 20: 357-65 and Tsuneyama et al., 1998, Hepatology 28: 620-3).
Methods directed to the manipulation of the NKT cell population in a subject that results in the modulation of the Th1/Th2 balance toward anti-inflammatory or pro-inflammatory cytokine producing cells. A detailed description of these inventions have been disclosed in U.S. patent application entitled “Educated NKT Cells and Their Uses in the Treatment of Immune-Related Disorders” by Yaron Ilan et al., filed on Jun. 25, 2003 (application Ser. No. 10/451,811), PCT Application No. IL01/01197, filed on Dec. 24, 2001, and U.S. application Ser. No. 10/375,906, filed on Feb. 27, 2003.
NAFLD
Obesity is strongly associated with non-alcoholic fatty liver disease (NAFLD), ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Hepatic steatosis (“first hit”) results from accumulation of lipids, predominantly triglycerides, within hepatocytes, due to variable combinations of excess lipid uptake and synthesis and altered lipid secretion. The transition from simple steatosis to NASH is thought to involve a “second hit”, usually attributed to oxidative stress (Day et al., 1998, Gastroenterology 114: 842-5).
The pathogenesis of non-alcoholic steatohepatitis (NASH) may also involve a number of immune mechanisms. A number of immunological derangements have been noted in leptin-deficient ob/ob mice, a murine model for NASH. These include impaired cell-mediated immunity (Howard et al., 1999, J Clin Invest 1999, 104:1051-9 and Lord et al., 1998, Nature 394:897-901), a reduction in the number of intrahepatic NKT lymphocytes (Guebre-Xabier et al., 2000, Hepatology 31: 633-640), impaired function of hepatic Kupffer cells (Lee et al., 1999, Am J Physiol 276:c386-c394), reduced serum levels of IL-10 and IL15, and increased serum levels of IL-12 (Loffreda et al., 1998, FASEB J 12:57-65; Li et al., 2002, Gastroenterology 2002; 123:1304-1310 and Tilg et al., 2000, N Eng J Med 343:1467-76). The reduced number of intrahepatic NKT lymphocytes in ob/ob mice may result from chronic oxidative stress that promotes increased apoptosis. Altered secretion of IL-15 by Kupffer cells, which is important for NKT cell differentiation, and decreased expression of leukocyte factor antigen 1 (LFA-1), necessary for hepatic accumulation of CD4+ NKT lymphocytes, were also suggested to be responsible for this defect (Kennedy et al., 2000, J Exp Med 191:771-780 and Takeda et al., 2000, Proc Natl Acad Sci USA 97:5498-5503). Leptin replenishment results in increased numbers of hepatic NKT lymphocytes, and partial reversal of the associated immune derangements in these animals.
At present, there is no effective therapy for NASH. Attempts have been made to target the underlying metabolic process by administration of a number of pharmacological agents, including vitamin E, metform in, pioglitazone, rosiglitazone, probucol and betaine (Brunt, 2004, Semin Liver Dis. 24:3-20), with variable effects on the hepatic fat content and serum aminotransferase levels. Current treatment approaches are directed primarily at achieving control of the metabolic conditions associated with NASH.
Glucocerebroside
Glucosylceramide is a naturally occurring glycolipid consisting of ceramide, to which glucose is attached. A ceramide, which is a sphingosine and a fatty acid, is the structural unit common to all sphingolipids. Sphingolipids have a variety of cellular functions. These include membrane structural roles and cell signaling participation. (Sullard et al., 2000 Journal of Mass Spectrometry 35:347-353.) Glucosylceramide is made by the enzyme glucosylceramide synthase which attaches the two molecules together (see FIG. 1 and FIG. 2). An example of a glucosylceramide includes glucocerebroside, or a glucocerebroside analogue or derivative. Mammalian glucocerbroside has a single trans double bond at position 4. Soy derived glucocerebroxide has two double bonds at positions 4 and 8 (65% trans, 35% cis) (Sullard et al., 2000, J Mass Spectrom 35:347-53).
The genetic disease Gaucher's Disease is characterized by an accumulation of glucosylceramide. In the treatment of this disorder by appropriate enzyme therapy, the excess glucosylceramide is degraded (Elstein et al., 2002, Paediatr Drugs 4:417-26). Two side effects of this treatment have been noted. In the course of this treatment, chronic active hepatitis associated with Hepatitis C virus infection was exacerbated. Additionally, certain patients (with pre-diabetic conditions) experienced the development of diabetic conditions, indicating an onset of Type II Diabetes. These observations further directly confirm that in human subjects, glucosylceramide levels regulate the onset of immune-mediated or immune-regulated disorders or diseases.